'Executes an UPDATE query on the named table, setting new values for
columns in a row matching the key values.
Args:
table : string giving the table name
keyvalues : dict of column names and values to select the row with
updatevalues : dict giving column names and values to update
retcols : optional list of column names to return
If present, retcols gives a list of column names on which to perform
a SELECT statement *before* performing the UPDATE statement. The values
of these will be returned in a dict.
These are performed within the same transaction, allowing an atomic
get-and-set.  This can be used to implement compare-and-set by putting
the update column in the \'keyvalues\' dict as well.'

def _simple_update_one(self, table, keyvalues, updatevalues, desc='_simple_update_one'):

    return self.runInteraction(desc, self._simple_update_one_txn, table, keyvalues, updatevalues)
