'Attempts to get implicit credentials in Google Compute Engine env.
If the current environment is not detected as Compute Engine, returns
None, indicating no Google Compute Engine credentials can be detected
from the current environment.
Returns:
None, if not in GCE, else a gce.AppAssertionCredentials object.'

@staticmethod
def _implicit_credentials_from_gce():

    if (not _in_gce_environment()):
        return None
    return _get_application_default_credential_GCE()
