'Constructor
@param format: format of date
@param past: how many months into the past the date can be set to
@param future: how many months into the future the date can be set to
@param start_field: "selector" for start date field
@param default_interval: x months from start date
@param default_explicit: bool for explicit default'

def __init__(self, format=None, past=None, future=None, start_field=None, default_interval=None, default_explicit=False):

    self.format = format
    self.past = past
    self.future = future
    self.start_field = start_field
    self.default_interval = default_interval
    self.default_explicit = default_explicit
