code: def __str__(self):
      prefix = "line %d: " % self.line_no if self.line_no else ""
      return "%s%s" % (prefix, self.message)
  
imports: import sys
  import traceback
label_desc: Use image node_id 2 for calling the MetaflowException obj's underlying member method code with example usage: obj.__str__() and returns: unknown