original_docstring: 
      Given a string str, reverse it omitting all non-alphabetic characters.
      
docstring: Given a string str, reverse it omitting all non-alphabetic characters.
docstring_tokens: Given a string str reverse it omitting all non - alphabetic characters .
code: def reverse_letter(string):
      """
      Given a string str, reverse it omitting all non-alphabetic characters.
      """
  
      return ''.join([ch for ch in string if ch.isalpha()][::-1])
code_tokens: def reverse_letter ( string ) : return '' . join ( [ ch for ch in string if ch . isalpha ( ) ] [ : : - 1 ] )
short_docstring: Given a string str, reverse it omitting all non-alphabetic characters.
short_docstring_tokens: Given a string str reverse it omitting all non - alphabetic characters .
comment: """
      Given a string str, reverse it omitting all non-alphabetic characters.
      """