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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 _render_section(self, output, params, indent=0):
 """ It takes a dictionary and recurses through. For key-value pair it checks whether the value is a dictionary and prepends the key with & It passes the valued to the same function, increasing the indentation If the value is a list, I assume that this is something the user wants to store repetitively eg: dict['KEY'] = ['val1', 'val2'] ===> KEY val1 KEY val2 or dict['KIND'] = [{'_': 'Ba', 'ELEMENT':'Ba'}, {'_': 'Ti', 'ELEMENT':'Ti'}, {'_': 'O', 'ELEMENT':'O'}] ====> &KIND Ba ELEMENT Ba &END KIND &KIND Ti ELEMENT Ti &END KIND &KIND O ELEMENT O &END KIND """


        for key, val in sorted(params.items()):
            if key.upper() != key:
                raise InputValidationError("keyword '%s' not upper case" % key)
            if key.startswith('@') or key.startswith('$'):
                raise InputValidationError("CP2K preprocessor not supported")
            if isinstance(val, dict):
                output.append('%s&%s %s' % (' ' * indent, key, val.pop('_', '')))
                self._render_section(output, val, indent + 3)
                output.append('%s&END %s' % (' ' * indent, key))
            elif isinstance(val, list):
                for listitem in val:
                    self._render_section(output, {key: listitem}, indent)
            elif isinstance(val, bool):
                val_str = '.true.' if val else '.false.'
                output.append('%s%s  %s' % (' ' * indent, key, val_str))
            else:
                output.append('%s%s  %s' % (' ' * indent, key, val))