def identity(requestContext, name, step=60):
    """
    Identity function:
    Returns datapoints where the value equals the timestamp of the datapoint.
    Useful when you have another series where the value is a timestamp, and
    you want to compare it to the time of the datapoint, to render an age

    Example::

        &target=identity("The.time.series")

    This would create a series named "The.time.series" that contains points
    where x(t) == t.

    Accepts optional second argument as 'step' parameter (default step is
    60 sec)
    """
    start = int(epoch(requestContext["startTime"]))
    end = int(epoch(requestContext["endTime"]))
    values = range(start, end, step)
    series = TimeSeries(name, start, end, step, values)
    series.pathExpression = 'identity("%s")' % name

    return [series]

    Identity function:
    Returns datapoints where the value equals the timestamp of the datapoint.
    Useful when you have another series where the value is a timestamp, and
    you want to compare it to the time of the datapoint, to render an age

    Example::

        &target=identity("The.time.series")

    This would create a series named "The.time.series" that contains points
    where x(t) == t.

    Accepts optional second argument as 'step' parameter (default step is
    60 sec)
    
graphite_api/functions.py