Process a single complete line.

def process_line(self, line):
        "Process a single complete line."
        cleaned = []
        columns = line.split(self.indel)
        # Populate indices if not defined
        if not self.indices:
            self.indices = range(len(columns))
        for i in self.indices:
            # Support turning an in col into multiple out cols
            out = self.process_column(i, columns[i])
            if isinstance(out, (list, tuple)):
                cleaned.extend(out)
            else:
                cleaned.append(out)
        return self.outdel.join(cleaned) + '\n'