#!/usr/bin/env python3

mfdir = '/usr/share/texlive/texmf-dist/fonts/source/public/amsfonts/symbols'

import re
import subprocess

def expand(fn):
  result = ''
  if fn.endswith(';'): fn = fn[:-1]
  with open(f'{mfdir}/{fn}.mf') as f:
    for line in f:
      if line[-1:] == '\n': line = line[:-1]
      line = line.split('%')[0]
      x = line.split()
      if len(x) == 2 and x[0] in ('generate','input'):
        result += expand(x[1])
        continue
      if x == ['wpix(1.90u)','(linethickness);']:
        line = 'wpix(3.40u) (linethickness);'
      r = re.match(r'^(.*)beginchar\(([^,]*),(.*)$',line)
      if r:
        line = r.group(1)+'beginchar('+r.group(2)+',21/20*'+r.group(3)
      result += line + '\n'
  return result

with open('bfbb.mf','w') as mf:
  mf.write(expand('msbm10'))

subprocess.run(['mf',r'\mode:=lexmarks; mag:=2.5; nonstopmode; input bfbb'],check=True)
subprocess.run(['mftrace','--format','ttf','--magnification','415.1100041511','bfbb'],check=True)