class_docstr: Keeps track of `Location` protos for pprof profile.
  
  `Locations` store information about function call locations.
docstr: Constructor.
  
  Args:
    functions: A `Functions` object.
docstr_tok: ["Constructor",".","Args",":","functions",":","A","`","Functions","`","object","."]
code: def __init__(self, functions):
      """Constructor.
  
      Args:
        functions: A `Functions` object.
      """
      self._functions = functions
      # Maps tuples in the form (file_path, called_function_name, line_number)
      # to `Location` protos.
      self._location_key_to_location = {}
  
imports: from collections import defaultdict
  from collections import namedtuple
  import gzip
  import os
  import string
  import sys
  import time
  from proto import profile_pb2
label_desc: Use image node_id 1 to create a new Locations object from inherited base classes: object with example: obj = Locations(functions)