%% The code below will print two warnings, which may be omitted by uncommenting:
%#(for-each (lambda (x) (ly:expect-warning "No string for pitch")) (iota 2))

mus = { 
  <c' bes'> 
  <c'\2 bes'> 
  \set maximumFretStretch = 5
  <c' bes'> 
  <c'\2 bes'\1> 
}

<<
  \new FretBoards \mus
  \new TabVoice \mus
>>