class_docstr: Result of spec parsing.
  
  ``functions'' is a mapping from function name to a tuple of signatures
  ``capsule'' is a mapping from function name to signature
code: def keys(self):
      return list(self.functions.keys()) + list(self.capsules.keys())
  
imports: from pythran.types.conversion import pytype_to_pretty_type
  from collections import defaultdict
  from itertools import product
  import re
  import ply.lex
  import ply.yacc
  from pythran.typing import List, Set, Dict, NDArray, Tuple, Pointer, Fun
  from pythran.syntax import PythranSyntaxError
  from pythran.config import cfg
label_desc: Use image node_id 2 for calling the Spec obj's underlying member method code with example usage: obj.keys() and returns: unknown