':param buffer: The media buffer
:param successful: True when the media has been loaded.
:type successful: bool
:param error: Error code
:type error: str
:param metadata: Dictionary of metadata about the buffer
:type metadata: dict'

def __init__(self, buffer=None, successful=True, error=None, metadata=dict()):

    self.buffer = buffer
    self.successful = successful
    self.error = error
    self.metadata = metadata
