class_docstr: Provide getitem syntax for functions
  
  >>> def inc(x):
  ...     return x + 1
  
  >>> I = IndexCallable(inc)
  >>> I[3]
  4
class_docstr_tok: ["Provide","getitem","syntax","for","functions",">",">",">","def","inc","(","x",")",":","...","return","x","+","1",">",">",">","I","=","IndexCallable","(","inc",")",">",">",">","I","[","3","]","4"]
code: def __getitem__(self, key):
      return self.fn(key)
  
file_path: datashader/datashader/datashape/internal_utils.py
imports: from __future__ import print_function, division, absolute_import
  import keyword
  import re
label_desc: Use image node_id 2 for calling the IndexCallable obj's underlying member method code with example usage: obj.__getitem__(key) and returns: self