message: Change 'must a Tensor' to 'must be a Tensor' in TypeError message
diff: @@ -3282,10 +3282,10 @@ def _indexed_case_verify_and_canonicalize_args(branch_fns, default,
  branch_fns: validated list of callables for each branch (default last).
  """
  if not isinstance(branch_index, ops.Tensor):
  - raise TypeError("branch_index must a Tensor, got {}".format(
  + raise TypeError("branch_index must be a Tensor, got {}".format(
  type(branch_index)))
  if not branch_index.dtype.is_integer:
  - raise TypeError("branch_index must an integer Tensor, got {}".format(
  + raise TypeError("branch_index must be an integer Tensor, got {}".format(
  branch_index.dtype))
  if not branch_fns:
  