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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 _replace_greek_characters(line):
 """Replace greek characters in a string."""

    for greek_char, replacement in iteritems(_GREEK_REPLACEMENTS):
        try:
            line = line.replace(greek_char, replacement)
        except UnicodeDecodeError:
            current_app.logger.exception("Unicode decoding error.")
            return ""
    return line