text: from django.core.exceptions import ValidationError
  
  
  def validate_only_letters(value):
      for char in value:
          if not char.isalpha():
              raise ValidationError('Value must contains only letters')
  
  
  def validate_file_max_size_in_mb(max_size):
      def validate(value):
          file_size = value.file.size
          if file_size > max_size * 1024 * 1024:
              raise ValidationError(f'Max file size is {max_size}MB')
  
      return validate
  