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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 _parse_numbers(text):
    '''
    Convert a string to a number, allowing for a K|M|G|T postfix, 32.8K.
    Returns a decimal number if the string is a real number,
    or the string unchanged otherwise.
    '''
    if text.isdigit():
        return decimal.Decimal(text)

    try:
        postPrefixes = {'K': '10E3', 'M': '10E6', 'G': '10E9', 'T': '10E12', 'P': '10E15', 'E': '10E18', 'Z': '10E21', 'Y': '10E24'}
        if text[-1] in postPrefixes.keys():
            v = decimal.Decimal(text[:-1])
            v = v * decimal.Decimal(postPrefixes[text[-1]])
            return v
        else:
            return decimal.Decimal(text)
    except ValueError:
        return text