def PpapiDispatchFunctionHeader(scope, type_defn, variable, npp, success):
  """Gets a header for PPAPI glue dispatch functions.

  This function creates a string containing a C++ code snippet that should be
  included at the beginning of PPAPI glue dispatch functions like Call or
  GetProperty. This code snippet will declare and initialize certain variables
  that will be used in the dispatch functions, like the pp::Var representing
  the object, or a pointer to the pp::Instance.

  Args:
    scope: a Definition for the scope in which the glue will be written.
    type_defn: a Definition, representing the type.
    variable: a string, representing a name of a variable that can be used to
      store a reference to the object.
    npp: a string, representing the name of the variable that holds the pointer
      to the pp::Instance. Will be declared by the code snippet.
    success: the name of a bool variable containing the current success status.
      (is not declared by the code snippet).

  Returns:
    a (string, string) pair, the first string being the code snippet, and the
    second string being an expression to access the object.
  """
  (scope, type_defn, success) = (scope, type_defn, success)  # silence gpylint.
  (variable, npp ) = (variable, npp) # silence gpylint.
  return ('', 'value_mutable()')