diff --git a/pykusto/query.py b/pykusto/query.py
index f5a89ba..b2f77f3 100644
--- a/pykusto/query.py
+++ b/pykusto/query.py
@@ -5,6 +5,8 @@ from itertools import chain
 from types import FunctionType
 from typing import Tuple, List, Union, Optional
 
+# noinspection PyProtectedMember
+from azure.kusto.data._response import KustoResponseDataSet
 from azure.kusto.data.helpers import dataframe_from_result_table
 
 from pykusto.client import Table
@@ -13,6 +15,7 @@ from pykusto.expressions import BooleanType, ExpressionType, AggregationExpressi
     AssignmentFromColumnToColumn, AnyExpression, to_kql, ColumnToType
 from pykusto.kql_converters import KQL
 from pykusto.logger import logger
+from pykusto.type_utils import TypeName
 from pykusto.udf import stringify_python_func
 
 
@@ -41,6 +44,12 @@ class JoinKind(Enum):
     RIGHTSEMI = "rightsemi"
 
 
+class Distribution(Enum):
+    SINGLE = 'single'
+    PER_NODE = 'per_node'
+    PER_SHARD = 'per_shard'
+
+
 class BagExpansion(Enum):
     BAG = "bag"
     ARRAY = "array"
@@ -54,7 +63,7 @@ class Query:
         self._head = head if isinstance(head, Query) else None
         self._table = head if isinstance(head, Table) else None
 
-    def __add__(self, other: 'Query'):
+    def __add__(self, other: 'Query') -> 'Query':
         self_copy = deepcopy(self)
         other_copy = deepcopy(other)
 
@@ -66,7 +75,7 @@ class Query:
         other_base._head = self_copy
         return other_copy
 
-    def __deepcopy__(self, memo):
+    def __deepcopy__(self, memo) -> 'Query':
         new_object = copy(self)
         if self._head is not None:
             new_object._head = self._head.__deepcopy__(memo)
@@ -96,7 +105,7 @@ class Query:
     def top(self, num_rows: int, col: Column, order: Order = None, nulls: Nulls = None) -> 'TopQuery':
         return TopQuery(self, num_rows, col, order, nulls)
 
-    def join(self, query: 'Query', kind: JoinKind = None):
+    def join(self, query: 'Query', kind: JoinKind = None) -> 'JoinQuery':
         return JoinQuery(self, query, kind)
 
     def project(self, *args: Union[Column, AssignmentBase, BaseExpression], **kwargs: ExpressionType) -> 'ProjectQuery':
@@ -121,13 +130,13 @@ class Query:
             assignments.append(AssignmentFromColumnToColumn(Column(column_name), column))
         return ProjectRenameQuery(self, assignments)
 
-    def project_away(self, *columns: StringType):
+    def project_away(self, *columns: StringType) -> 'ProjectAwayQuery':
         return ProjectAwayQuery(self, columns)
 
-    def distinct(self, *columns: BaseExpression):
+    def distinct(self, *columns: BaseExpression) -> 'DistinctQuery':
         return DistinctQuery(self, columns)
 
-    def distinct_all(self):
+    def distinct_all(self) -> 'DistinctQuery':
         return DistinctQuery(self, (AnyExpression(KQL("*")),))
 
     def extend(self, *args: Union[BaseExpression, AssignmentBase], **kwargs: ExpressionType) -> 'ExtendQuery':
@@ -159,17 +168,29 @@ class Query:
         return SummarizeQuery(self, assignments)
 
     def mv_expand(self, *columns: Union[Column, ColumnToType], bag_expansion: BagExpansion = None, with_item_index: Column = None,
-                  limit: int = None):
+                  limit: int = None) -> 'MvExpandQuery':
         if len(columns) == 0:
             raise ValueError("Please specify one or more columns for mv-expand")
         return MvExpandQuery(self, columns, bag_expansion, with_item_index, limit)
 
-    def custom(self, custom_query: str):
+    def custom(self, custom_query: str) -> 'CustomQuery':
         return CustomQuery(self, custom_query)
 
-    # TODO convert python types to kusto types
-    def evaluate(self, udf: FunctionType, type_spec_str: str):
-        return EvaluatePythonQuery(self, udf, type_spec_str)
+    def evaluate(self, plugin_name, *args: ExpressionType, distribution: Distribution = None) -> 'EvaluateQuery':
+        return EvaluateQuery(self, plugin_name, *args, distribution=distribution)
+
+    def evaluate_udf(self, udf: FunctionType, extend: bool = True, distribution: Distribution = None, **type_specs: TypeName) -> 'EvaluateQuery':
+        return EvaluateQuery(
+            self, 'python',
+            BaseExpression(KQL('typeof({})'.format(('*, ' if extend else '') + ', '.join(field_name + ':' + type_name.value for field_name, type_name in type_specs.items())))),
+            stringify_python_func(udf),
+            distribution=distribution
+        )
+
+    def bag_unpack(self, col: Column, prefix: str = None) -> 'EvaluateQuery':
+        if prefix is None:
+            return EvaluateQuery(self, 'bag_unpack', col)
+        return EvaluateQuery(self, 'bag_unpack', col, prefix)
 
     @abstractmethod
     def _compile(self) -> KQL:
@@ -199,7 +220,7 @@ class Query:
         logger.debug("Complied query: " + result)
         return result
 
-    def execute(self, table: Table = None):
+    def execute(self, table: Table = None) -> KustoResponseDataSet:
         if self.get_table() is None:
             if table is None:
                 raise RuntimeError("No table supplied")
@@ -510,17 +531,20 @@ class CustomQuery(Query):
         return KQL(self._custom_query)
 
 
-class EvaluatePythonQuery(Query):
-    _udf: FunctionType
-    _type_specs: str
+class EvaluateQuery(Query):
+    _plugin_name: str
+    _args: Tuple[ExpressionType]
+    _distribution: Distribution
 
-    def __init__(self, head: Query, udf: FunctionType, type_specs: str):
-        super(EvaluatePythonQuery, self).__init__(head)
-        self._udf = udf
-        self._type_specs = type_specs
+    def __init__(self, head: Query, plugin_name: str, *args: ExpressionType, distribution: Distribution = None):
+        super().__init__(head)
+        self._plugin_name = plugin_name
+        self._args = args
+        self._distribution = distribution
 
     def _compile(self) -> KQL:
-        return KQL('evaluate python({},"{}")'.format(
-            self._type_specs,
-            stringify_python_func(self._udf)
+        return KQL('evaluate {}{}({})'.format(
+            '' if self._distribution is None else 'hint.distribution={} '.format(self._distribution.value),
+            self._plugin_name,
+            ', '.join(to_kql(arg) for arg in self._args),
         ))

diff --git a/test/test_query.py b/test/test_query.py
index ba09eaa..e5911ea 100644
--- a/test/test_query.py
+++ b/test/test_query.py
@@ -1,10 +1,11 @@
 from pykusto import functions as f
 from pykusto.client import PyKustoClient
 from pykusto.expressions import column_generator as col
-from pykusto.query import Query, Order, Nulls, JoinKind, JoinException, BagExpansion
+from pykusto.query import Query, Order, Nulls, JoinKind, JoinException, BagExpansion, Distribution
 from pykusto.type_utils import TypeName
 from test.test_base import TestBase
 from test.test_table import MockKustoClient
+from test.udf import func, STRINGIFIED
 
 
 class TestQuery(TestBase):
@@ -290,14 +291,38 @@ class TestQuery(TestBase):
             Query().distinct_all().render(),
         )
 
+    def test_evaluate(self):
+        self.assertEqual(
+            " | evaluate some_plugin(foo, 3)",
+            Query().evaluate('some_plugin', col.foo, 3).render(),
+        )
+
+    def test_evaluate_with_distribution(self):
+        self.assertEqual(
+            " | evaluate hint.distribution=per_shard some_plugin(foo, 3)",
+            Query().evaluate('some_plugin', col.foo, 3, distribution=Distribution.PER_SHARD).render(),
+        )
+
     def test_udf(self):
-        # noinspection PyGlobalUndefined
-        def func():
-            global result
-            global df
+        self.assertEqual(
+            " | evaluate python(typeof(*, StateZone:string), {})".format(STRINGIFIED),
+            Query().evaluate_udf(func, StateZone=TypeName.STRING).render(),
+        )
 
-            result = df
-            result['StateZone'] = result["State"] + result["Zone"]
+    def test_udf_no_extend(self):
+        self.assertEqual(
+            " | evaluate python(typeof(StateZone:string), {})".format(STRINGIFIED),
+            Query().evaluate_udf(func, extend=False, StateZone=TypeName.STRING).render(),
+        )
 
-        # TODO assert
-        Query().evaluate(func, "typeof(*, StateZone: string)").render()
+    def test_bag_unpack(self):
+        self.assertEqual(
+            " | evaluate bag_unpack(foo)",
+            Query().bag_unpack(col.foo).render(),
+        )
+
+    def test_bag_unpack_with_prefix(self):
+        self.assertEqual(
+            ' | evaluate bag_unpack(foo, "bar_")',
+            Query().bag_unpack(col.foo, 'bar_').render(),
+        )
diff --git a/test/udf.py b/test/udf.py
new file mode 100644
index 0000000..c0c7b02
--- /dev/null
+++ b/test/udf.py
@@ -0,0 +1,17 @@
+# Function for testing python evaluation plugin, with the result of stringification given below.
+# Kept in a separate file because any change to the function (even whitespace) might cause the stringified text to change.
+
+
+# noinspection PyGlobalUndefined
+def func():
+    global result
+    global df
+
+    result = df
+    result['StateZone'] = result["State"] + result["Zone"]
+
+
+STRINGIFIED = "\"from types import CodeType\\n" \
+              "code=CodeType(0,0,0,3,67,b't\\\\x00a\\\\x01t\\\\x01d\\\\x01\\\\x19\\\\x00t\\\\x01d\\\\x02\\\\x19\\\\x00\\\\x17\\\\x00t\\\\x01d\\\\x03<\\\\x00d\\\\x00S\\\\x00'," \
+              "(None, 'State', 'Zone', 'StateZone'),('df', 'result'),(),'{}','func',6,b'\\\\x00\\\\x04\\\\x04\\\\x01',(),())\\n" \
+              "exec(code)\\n\"".format(__file__)

Allow using "evaluate" operator for plugins other than python
test/test_query.py::TestQuery::test_add_queries test/test_query.py::TestQuery::test_add_queries_with_table test/test_query.py::TestQuery::test_bag_unpack test/test_query.py::TestQuery::test_bag_unpack_with_prefix test/test_query.py::TestQuery::test_count test/test_query.py::TestQuery::test_custom test/test_query.py::TestQuery::test_distinct test/test_query.py::TestQuery::test_distinct_all test/test_query.py::TestQuery::test_evaluate test/test_query.py::TestQuery::test_evaluate_with_distribution test/test_query.py::TestQuery::test_extend test/test_query.py::TestQuery::test_extend_assign_to_multiple_columns test/test_query.py::TestQuery::test_extend_generate_column_name test/test_query.py::TestQuery::test_join_no_joined_table test/test_query.py::TestQuery::test_join_no_on test/test_query.py::TestQuery::test_join_with_table test/test_query.py::TestQuery::test_join_with_table_and_query test/test_query.py::TestQuery::test_limit test/test_query.py::TestQuery::test_mv_expand test/test_query.py::TestQuery::test_mv_expand_args test/test_query.py::TestQuery::test_mv_expand_no_args test/test_query.py::TestQuery::test_mv_expand_to_type test/test_query.py::TestQuery::test_no_params_for_sort test/test_query.py::TestQuery::test_order test/test_query.py::TestQuery::test_order_expression_in_arg test/test_query.py::TestQuery::test_project test/test_query.py::TestQuery::test_project_assign_to_multiple_columns test/test_query.py::TestQuery::test_project_away test/test_query.py::TestQuery::test_project_away_wildcard test/test_query.py::TestQuery::test_project_rename test/test_query.py::TestQuery::test_project_unspecified_column test/test_query.py::TestQuery::test_project_with_expression test/test_query.py::TestQuery::test_sample test/test_query.py::TestQuery::test_sanity test/test_query.py::TestQuery::test_sort test/test_query.py::TestQuery::test_sort_multiple_cols test/test_query.py::TestQuery::test_summarize test/test_query.py::TestQuery::test_summarize_by test/test_query.py::TestQuery::test_summarize_by_expression test/test_query.py::TestQuery::test_take test/test_query.py::TestQuery::test_top test/test_query.py::TestQuery::test_udf test/test_query.py::TestQuery::test_udf_no_extend test/test_query.py::TestQuery::test_where