@property<EOL><INDENT>def parent_images(self):<DEDENT>
parents = []<EOL>for instr in self.structure:<EOL><INDENT>if instr['<STR_LIT>'] != '<STR_LIT>':<EOL><INDENT>continue<EOL><DEDENT>image, _ = image_from(instr['<STR_LIT:value>'])<EOL>if image is not None:<EOL><INDENT>parents.append(image)<EOL><DEDENT><DEDENT>return parents<EOL>
:return: list of parent images -- one image per each stage's FROM instruction