<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def native(self, value, context=None):
 		"""Convert a foreign value to a native boolean."""

		
		value = super().native(value, context)
		
		if self.none and (value is None):
			return None
		
		try:
			value = value.lower()
		except AttributeError:
			return bool(value)
		
		if value in self.truthy:
			return True
		
		if value in self.falsy:
			return False
		
		raise Concern("Unable to convert {0!r} to a boolean value.", value)