'Overridable hashcode generation for invoice lines. Lines having the same hashcode
will be grouped together if the journal has the \'group line\' option. Of course a module
can add fields to invoice lines that would need to be tested too before merging lines
or not.'

def inv_line_characteristic_hashcode(self, invoice_line):

    return ('%s-%s-%s-%s-%s-%s-%s' % (invoice_line['account_id'], invoice_line.get('tax_ids', 'False'), invoice_line.get('tax_line_id', 'False'), invoice_line.get('product_id', 'False'), invoice_line.get('analytic_account_id', 'False'), invoice_line.get('date_maturity', 'False'), invoice_line.get('analytic_tag_ids', 'False')))
