docs: def foreign(self, value, context=None):
  		"""Convert a native value to a textual boolean."""
  		
  		if self.none and value is None:
  			return ''
  		
  		try:
  			value = self.native(value, context)
  		except Concern:
  			# The value might not be in the lists; bool() evaluate it instead.
  			value = bool(value.strip() if self.strip and hasattr(value, 'strip') else value)
  		
  		if value in self.truthy or value:
  			return self.truthy[self.use]
  		
  		return self.falsy[self.use]