Reduce indentation from four spaces to a single TAB

[joente]

Is your feature request related to a problem? Please describe.
The current format function uses four spaces as indentation. Since the indentation has quite an impact on the size of exports and prints, it would be useful to reduce the characters used for indentation. This way we keep good readability while saving some characters.

Describe the solution you'd like
Use a single TAB as this reduces the size dramatically while keeping the export readable.

Describe alternatives you've considered
Use indentation of two spaces instead of four.