def export(self, out_file: str, layer: str = None, format: str = "<STR_LIT>") -> None:
if format != "<STR_LIT>":<EOL><INDENT>raise NotImplementedError("<STR_LIT>")<EOL><DEDENT>with open(out_file, "<STR_LIT:w>") as f:<EOL><INDENT>for ca in self.col_attrs.keys():<EOL><INDENT>for ra in self.row_attrs.keys():<EOL><INDENT>f.write("<STR_LIT:\t>")<EOL><DEDENT>f.write(ca + "<STR_LIT:\t>")<EOL>for v in self.col_attrs[ca]:<EOL><INDENT>f.write(str(v) + "<STR_LIT:\t>")<EOL><DEDENT>f.write("<STR_LIT:\n>")<EOL><DEDENT>for ra in self.row_attrs.keys():<EOL><INDENT>f.write(ra + "<STR_LIT:\t>")<EOL><DEDENT>f.write("<STR_LIT:\t>")<EOL>for v in range(self.shape[<NUM_LIT:1>]):<EOL><INDENT>f.write("<STR_LIT:\t>")<EOL><DEDENT>f.write("<STR_LIT:\n>")<EOL>for row in range(self.shape[<NUM_LIT:0>]):<EOL><INDENT>for ra in self.row_attrs.keys():<EOL><INDENT>f.write(str(self.row_attrs[ra][row]) + "<STR_LIT:\t>")<EOL><DEDENT>f.write("<STR_LIT:\t>")<EOL>if layer is None:<EOL><INDENT>for v in self[row, :]:<EOL><INDENT>f.write(str(v) + "<STR_LIT:\t>")<EOL><DEDENT><DEDENT>else:<EOL><INDENT>for v in self.layers[layer][row, :]:<EOL><INDENT>f.write(str(v) + "<STR_LIT:\t>")<EOL><DEDENT><DEDENT>f.write("<STR_LIT:\n>")<EOL><DEDENT><DEDENT>
Export the specified layer and row/col attributes as tab-delimited file.

Args:
        out_file:	Path to the output file
        layer:	Name of the layer to export, or None to export the main matrix
        format: Desired file format (only 'tab' is supported)