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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 decode_text(s):
 """Decodes a PDFDocEncoding string to Unicode."""

    if s.startswith(b'\xfe\xff'):
        return unicode(s[2:], 'utf-16be', 'ignore')
    else:
        return ''.join(PDFDocEncoding[ord(c)] for c in s)