Consumes input extracting definitions.

    Args:
      a_file: The file like stream to parse.

    Raises:
      PDDMError if there are any issues.

def ParseInput(self, a_file):
    """Consumes input extracting definitions.

    Args:
      a_file: The file like stream to parse.

    Raises:
      PDDMError if there are any issues.
    """
    input_lines = a_file.read().splitlines()
    self.ParseLines(input_lines)