'Updates the policy that grants an entity permission to assume a role.
Currently, only an Amazon EC2 instance can assume a role.
:type role_name: string
:param role_name: Name of the role to update.
:type policy_document: string
:param policy_document: The policy that grants an entity permission to
assume the role.'

def update_assume_role_policy(self, role_name, policy_document):

    return self.get_response('UpdateAssumeRolePolicy', {'RoleName': role_name, 'PolicyDocument': policy_document})
