add __str__ methods to queryLineage results

Author: Yi-Ting Lee

src/sagemaker/lineage/query.py

@@ -92,6 +92,10 @@ def __eq__(self, other):
             and self.destination_arn == other.destination_arn
         )
 
+    def __str__(self):
+        """Define string representation of `Edge`."""
+        return (str(self.__dict__))
+
 
 class Vertex:
     """A vertex for a lineage graph."""
@@ -130,6 +134,10 @@ def __eq__(self, other):
             and self.lineage_source == other.lineage_source
         )
 
+    def __str__(self):
+        """Define string representation of `Vertex`."""
+        return (str(self.__dict__))
+
     def to_lineage_object(self):
         """Convert the ``Vertex`` object to its corresponding lineage object.
 
@@ -199,6 +207,12 @@ def __init__(
         if vertices is not None:
             self.vertices = vertices
 
+    def __str__(self):
+        """Define string representation of `LineageQueryResult`."""
+        result_dict = vars(self)
+        
+        return (str({k: [vars(val) for val in v] for k, v in result_dict.items()}))
+
 
 class LineageFilter(object):
     """A filter used in a lineage query."""