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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_field(parsing_scheme, html_data, field, index=0):
 """ Parse an HTML table to find the requested field's value. All of the values are passed in an HTML table row instead of as individual items. The values need to be parsed by matching the requested attribute with a parsing scheme that sports-reference uses to differentiate stats. This function returns a single value for the given attribute. Parameters parsing_scheme : dict A dictionary of the parsing scheme to be used to find the desired field. The key corresponds to the attribute name to parse, and the value is a PyQuery-readable parsing scheme as a string (such as 'td[data-stat="wins"]'). html_data : string A string containing all of the rows of stats for a given team. If multiple tables are being referenced, this will be comprised of multiple rows in a single string. field : string The name of the attribute to match. Field must be a key in parsing_scheme. index : int (optional) An optional index if multiple fields have the same attribute name. For example, 'HR' may stand for the number of home runs a baseball team has hit, or the number of home runs a pitcher has given up. The index aligns with the order in which the attributes are recevied in the html_data parameter. Returns ------- string The value at the specified index for the requested field. If no value could be found, returns None. """

    if field == 'abbreviation':
        return _parse_abbreviation(html_data)
    scheme = parsing_scheme[field]
    items = [i.text() for i in html_data(scheme).items()]
    # Stats can be added and removed on a yearly basis. If not stats are found,
    # return None and have the be the value.
    if len(items) == 0:
        return None
    # Default to returning the first element. Optionally return another element
    # if multiple fields have the same tag attribute.
    try:
        return items[index]
    except IndexError:
        return None