class_docstr: AST Visitor that processes function calls.
  
  Updates function calls from old API version to new API version using a given
  change spec.
class_docstr_tok: ["AST","Visitor","that","processes","function","calls",".","Updates","function","calls","from","old","API","version","to","new","API","version","using","a","given","change","spec","."]
code: def __init__(self, api_change_spec):
      self._api_change_spec = api_change_spec
      self._log = []  # Holds 4-tuples: severity, line, col, msg.
      self._stack = []
  
imports: import ast
  import collections
  import os
  import re
  import shutil
  import sys
  import tempfile
  import traceback
  import pasta
label_desc: Use image node_id 1 to create a new _PastaEditVisitor object from inherited base classes: ast with example: obj = _PastaEditVisitor(api_change_spec)