code: func (f *Fpdf) SetLeftMargin(margin float64) {
  	f.lMargin = margin
  	if f.page > 0 && f.x < margin {
  		f.x = margin
  	}
  }
docs: // SetLeftMargin defines the left margin. The method can be called before
  // creating the first page. If the current abscissa gets out of page, it is
  // brought back to the margin.