  The exec statement  Execute Python code.   exec expression
exec expression in expression [, expression]  This statement
supports dynamic execution of Python code. The first expression
should evaluate to either a string, an open file object, or a
code object. If it is a string, the string is parsed as a suite
of Python statements which is then executed (unless a syntax
error occurs). If it is an open file, the file is parsed until
EOF and executed. If it is a code object, it is simply executed.
In all cases, the code that’s executed is expected to be valid
as file input (see section 8.2, “File input”). Be aware that the
return and yield statements may not be used outside of function
definitions even within the context of code passed to the exec
statement.  In all cases, if the optional parts are omitted, the
code is executed in the current scope. If only the first
expression after in is specified, it should be a dictionary,
which will be used for both the global and the local variables.
If two expressions