Initialize a new (min,max) tuple interval from values.

    Args:
        *vals ([int,...]):  A list of values (or Nones)

    Returns:
        ((int,int)):    A (min,max) interval tuple or None

def fold(*vals):
    '''
    Initialize a new (min,max) tuple interval from values.

    Args:
        *vals ([int,...]):  A list of values (or Nones)

    Returns:
        ((int,int)):    A (min,max) interval tuple or None

    '''
    vals = [v for v in vals if v is not None]
    if not vals:
        return None
    return min(vals), max(vals)