'Set details for a function argument'

def __init__(self, name, citdl=None, signature=None, default=None):

    self.name = name
    self.citdl = citdl
    if signature:
        self.signature = signature
    elif citdl:
        self.signature = ('%s    $%s' % (citdl, name))
    else:
        self.signature = ('$%s' % (name,))
    self.default = default
