class_docstr: Gather all kind of identifier defined at global scope.
  
  >>> import gast as ast
  >>> from pythran import passmanager
  >>> from pythran.analyses import GlobalDeclarations
  >>> node = ast.parse('''
  ... import math
  ... import math as maths
  ... from math import cos
  ... c = 12
  ... def foo(a):
  ...     b = a + 1''')
  >>> pm = passmanager.PassManager("test")
  >>> sorted(pm.gather(GlobalDeclarations, node).keys())
  ['c', 'cos', 'foo', 'math', 'maths']
docstr: Import module define a new variable name. 
docstr_tok: ["Import","module","define","a","new","variable","name","."]
code: def visit_FunctionDef(self, node):
      """Import module define a new variable name."""
      self.result[node.name] = node
  
file_path: catboost/contrib/python/pythran/pythran/analyses/global_declarations.py
imports: import gast
  from pythran.passmanager import ModuleAnalysis
label_desc: Use image node_id 2 for calling the GlobalDeclarations obj's underlying member method code with example usage: obj.visit_FunctionDef(node) without return types