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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 header_encode(header_bytes, charset='iso-8859-1'):
 """Encode a single header line with Base64 encoding in a given charset. charset names the character set to use to encode the header. It defaults to iso-8859-1. Base64 encoding is defined in RFC 2045. """

    if not header_bytes:
        return ""
    if isinstance(header_bytes, str):
        header_bytes = header_bytes.encode(charset)
    encoded = b64encode(header_bytes).decode("ascii")
    return '=?%s?b?%s?=' % (charset, encoded)