'Creates a new role for your AWS account.
The policy grants permission to an EC2 instance to assume the role.
The policy is URL-encoded according to RFC 3986. Currently, only EC2
instances can assume roles.
:type role_name: string
:param role_name: Name of the role to create.
:type assume_role_policy_document: ``string`` or ``dict``
:param assume_role_policy_document: The policy that grants an entity
permission to assume the role.
:type path: string
:param path: The path to the role.'

def create_role(self, role_name, assume_role_policy_document=None, path=None):

    params = {'RoleName': role_name, 'AssumeRolePolicyDocument': self._build_policy(assume_role_policy_document)}
    if (path is not None):
        params['Path'] = path
    return self.get_response('CreateRole', params)
