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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 construct_xray_header(headers):
 """ Construct a ``TraceHeader`` object from dictionary headers of the incoming request. This method should always return a ``TraceHeader`` object regardless of tracing header's presence in the incoming request. """

    header_str = headers.get(http.XRAY_HEADER) or headers.get(http.ALT_XRAY_HEADER)
    if header_str:
        return TraceHeader.from_header_str(header_str)
    else:
        return TraceHeader()