'Begin the validation process for the given number.
Returns a dictionary with the following keys
**account_sid**:
The unique id of the Account to which the Validation Request belongs.
**phone_number**: The incoming phone number being validated,
formatted with a \'+\' and country code e.g., +16175551212
**friendly_name**: The friendly name you provided, if any.
**validation_code**: The 6 digit validation code that must be entered
via the phone to validate this phone number for Caller ID.
:param phone_number: The phone number to call and validate
:param friendly_name: A description for the new caller ID
:param call_delay: Number of seconds to delay the validation call.
:param extension: Digits to dial after connecting the validation call.
:returns: A response dictionary'

def validate(self, phone_number, **kwargs):

    kwargs['phone_number'] = phone_number
    params = transform_params(kwargs)
    (resp, validation) = self.request('POST', self.uri, data=params)
    return validation
