parameters: (self, prefix)
return_statement: return None
docstring: find an extra token starting with the given prefix
docstring_summary: find an extra token starting with the given prefix
docstring_tokens: find an extra token starting with the given prefix
function: def extra_prefix(self, prefix):
          '''find an extra token starting with the given prefix'''
          for e in self.extra:
              if e.startswith(prefix):
                  return e
          return None
function_tokens: def extra_prefix ( self , prefix ) : for e in self . extra : if e . startswith ( prefix ) : return e return None