fpdf setting thickness of a line

Question

According to what the fpdf author says, the method for setting the thickness of a line is as follows:

SetLineWidth
       SetLineWidth(float width)
Description
       Defines the line width. By default, the value equals 0.2 mm. The method can be called before the first page is created and the value is retained from page to page.
Parameters
       width
          The width.

My code

pdf = FPDF('W', 'mm', 'A4')
pdf.alias_nb_pages()
pdf.SetLineWidth(0.1)

and the error I get:

Exception has occurred: AttributeError
'FPDF' object has no attribute 'SetLineWidth'

After some tests I understood that pyfpdf does not accept this method so... is there another method to vary the thickness of the lines? In my case they would be the borders of a cell

pdf.cell(6, jump, item, 'LTB', 0, 'C')