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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 highlight(str1, str2):
 """Highlight str1 with the contents of str2."""

    print('------------------------------')
    try:
        str2 = str2[0]
    except IndexError:
        str2 = None
    if str1 and str2:
        return str1.replace(str2, "<b>{}</b>".format(str2))
    else:
        return str1