Note: google_cloudfunctions_function_iam_policy cannot be used in conjunction with google_cloudfunctions_function_iam_binding and google_cloudfunctions_function_iam_member or they will fight over what your policy should be.
Note: google_cloudfunctions_function_iam_binding resources can be used in conjunction with google_cloudfunctions_function_iam_member resources only if they do not grant privilege to the same role.
See https://www.terraform.io/docs/providers/google/r/cloudfunctions_cloud_function_iam.html