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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_roles(client):
 """Returns a list of all the roles for an account. Returns a list containing all the roles for the account. Args: client (:obj:`boto3.session.Session`):
 A boto3 Session object Returns: :obj:`list` of `dict` """

        done = False
        marker = None
        roles = []

        while not done:
            if marker:
                response = client.list_roles(Marker=marker)
            else:
                response = client.list_roles()

            roles += response['Roles']

            if response['IsTruncated']:
                marker = response['Marker']
            else:
                done = True

        return roles