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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Note that you have to execute the command jupyter notebook in the parent directory of 
this directory for otherwise jupyter won't be able to access the file style.css.
Step1:  This example has been extracted from the official documentation of Ply.
A Tokenizer for Numbers and the Arithmetical Operators
The module ply.lex contains the code that is necessary to create a scanner.
Step2:  We start with a definition of the <em style="color
Step3:  There are two ways to define these tokens
Step4:  If we need to transform a token, we can define the token via a function.  In that case, the first line of the function 
has to be a string that is a regular expression.  This regular expression then defines the token.  After that,
we can add code to transform the token.  The string that makes up the token is stored in t.value.  Below, this string
is transformed into an integer via the predefined function int.
Step5:  The rule below is used to keep track of line numbers. We use the function length since there might be
more than one newline.  The member variable lexer.lineno keeps track ofthe current line number.  This
is needed for error messages.
Step6:  The keyword t_ignore specifies those characters that should be discarded.
In this case, spaces and tabs are ignored.  Note that we cannot use a raw string here.
Step7:  All characters not recognized by any of the defined tokens are handled by the function t_error.
The function t.lexer.skip(1) skips the character that has not been recognized. Scanning resumes 
after this character has been discarded.
Step8:  Below the function lex.lex() creates the lexer specified above.  Since this code is expected to be part 
of some python file but really isn't since it is placed in a Jupyter notebook we have to set the variable 
__file__ manually to fool the system into believing that the code given above is located in a file 
called hugo.py.  Of course, the name hugo is totally irrelevant and could be replaced by any other name.
Step10:  Lets test the generated scanner, that is stored in lexer, with the following string
Step11:  Let us feed the scanner with the string data.  This is done by calling the method input of the generated scanner.
Step12:  Now we put the lexer to work by using it as an iterable.  This way, we can simply iterate over all the tokens that our scanner recognizes.
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Python Code:
from IPython.core.display import HTML
with open ("../style.css", "r") as file:
    css = file.read()
HTML(css)
Explanation: Note that you have to execute the command jupyter notebook in the parent directory of 
this directory for otherwise jupyter won't be able to access the file style.css.
End of explanation
import ply.lex as lex
Explanation: This example has been extracted from the official documentation of Ply.
A Tokenizer for Numbers and the Arithmetical Operators
The module ply.lex contains the code that is necessary to create a scanner.
End of explanation
tokens = [
   'NUMBER',
   'PLUS',
   'MINUS',
   'TIMES',
   'DIVIDE',
   'LPAREN',
   'RPAREN'
]
Explanation: We start with a definition of the <em style="color:blue">token names</em>.  Note that all token names have to start with 
a capital letter.  We have to define these token names as a list with the name tokens:
End of explanation
t_PLUS    = r'\+'
t_MINUS   = r'-'
t_TIMES   = r'\*'
t_DIVIDE  = r'/'
t_LPAREN  = r'\('
t_RPAREN  = r'\)'
Explanation: There are two ways to define these tokens:
 - immediate token definitions define the token by assigning a regular expression to a variable of the form t_name,
   where name is the name of the token that is defined.
 - functional token definitions define the token via a function.  The regular expression that defines the token
   is the string appearing in the first line of the function body.
We see examples below.  We start with the immediate token definitions.  Note that we have to use raw strings here to prevent 
the expansion of backslash sequences.  Furthermore, operator symbols have to be escaped with a backslash character.
End of explanation
def t_NUMBER(t):
    r'0|[1-9][0-9]*'
    t.value = int(t.value)
    return t
Explanation: If we need to transform a token, we can define the token via a function.  In that case, the first line of the function 
has to be a string that is a regular expression.  This regular expression then defines the token.  After that,
we can add code to transform the token.  The string that makes up the token is stored in t.value.  Below, this string
is transformed into an integer via the predefined function int.
End of explanation
def t_newline(t):
    r'\n+'
    t.lexer.lineno += len(t.value)
Explanation: The rule below is used to keep track of line numbers. We use the function length since there might be
more than one newline.  The member variable lexer.lineno keeps track ofthe current line number.  This
is needed for error messages.
End of explanation
t_ignore = ' \t'
Explanation: The keyword t_ignore specifies those characters that should be discarded.
In this case, spaces and tabs are ignored.  Note that we cannot use a raw string here.
End of explanation
def t_error(t):
    print(f"Illegal character {t.value[0]} at line {t.lexer.lineno}.")
    t.lexer.skip(1)
Explanation: All characters not recognized by any of the defined tokens are handled by the function t_error.
The function t.lexer.skip(1) skips the character that has not been recognized. Scanning resumes 
after this character has been discarded.
End of explanation
__file__ = 'hugo'
lexer = lex.lex()
Explanation: Below the function lex.lex() creates the lexer specified above.  Since this code is expected to be part 
of some python file but really isn't since it is placed in a Jupyter notebook we have to set the variable 
__file__ manually to fool the system into believing that the code given above is located in a file 
called hugo.py.  Of course, the name hugo is totally irrelevant and could be replaced by any other name.
End of explanation
data = 3 + 4 * 10 + 007 + (-20) * 2
          3 + 4 * 10 + abc + (-20) * 2
       
Explanation: Lets test the generated scanner, that is stored in lexer, with the following string:
End of explanation
lexer.input(data)
Explanation: Let us feed the scanner with the string data.  This is done by calling the method input of the generated scanner.
End of explanation
for tok in lexer:
    print(tok)
Explanation: Now we put the lexer to work by using it as an iterable.  This way, we can simply iterate over all the tokens that our scanner recognizes.
End of explanation
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