class_docstr: A Setting for text entries of size one
      
class_docstr_tok: ["A","Setting","for","text","entries","of","size","one"]
docstr: Restrict value to single character
          
docstr_tok: ["Restrict","value","to","single","character"]
code: def test_valid(self, pipeline):
      """Restrict value to single character"""
      super().test_valid(pipeline)
      if len(self.value) > 1:
          raise ValidationError(
              "Only single characters can be used.", self
          )
  
imports: from ._alphanumeric import Alphanumeric
  from ..._validation_error import ValidationError
label_desc: Use image node_id 2 for calling the Character obj's underlying member method code with example usage: obj.test_valid(pipeline) without return types