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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def load(self, content):
 """Loads Command Definitions from the given YAML content into into this Command Dictionary. Content may be either a filename containing YAML content or a YAML string. Load has no effect if this Command Dictionary was already instantiated with a filename or YAML content. """

        if self.filename is None:
            if os.path.isfile(content):
                self.filename = content
                stream        = open(self.filename, 'rb')
            else:
                stream        = content

            for cmd in yaml.load(stream):
                self.add(cmd)

            if type(stream) is file:
                stream.close()