new_contents: from django.core.validators import RegexValidator, validate_email
  from django.core.exceptions import ValidationError
  
  
  def validate(fieldname, value):
      validator_name = 'validate_%s' % fieldname
      if validator_name in globals():
          globals()[validator_name](value)
  
  
  validate_mobile_number = RegexValidator(regex=r'^[\+]?[0-9]*$')
  validate_login_alias = RegexValidator(regex=r'[^ +A-Z]{4,}')
  
subject: add basic field validation functions - to be expanded