import sysimport csvimport structimport datetimeimport decimalimport itertoolsfrom cStringIO import StringIOfrom operator import itemgetterdef dbfreader(f):    """Returns an iterator over records in a Xbase DBF file.    The first row returned contains the field names.    The second row contains field specs: (type, size, decimal places).    Subsequent rows contain the data records.    If a record is marked as deleted, it is skipped.    File should be opened for binary reads.    """    # See DBF format spec at:    #     http://www.pgts.com.au/download/public/xbase.htm#DBF_STRUCT    numrec, lenheader = struct.unpack('