code: def generate(env):
      
      global PDFTeXAction
      if PDFTeXAction is None:
          PDFTeXAction = SCons.Action.Action('$PDFTEXCOM', '$PDFTEXCOMSTR')
  
      global PDFLaTeXAction
      if PDFLaTeXAction is None:
          PDFLaTeXAction = SCons.Action.Action("$PDFLATEXCOM", "$PDFLATEXCOMSTR")
  
      global PDFTeXLaTeXAction
      if PDFTeXLaTeXAction is None:
          PDFTeXLaTeXAction = SCons.Action.Action(PDFTeXLaTeXFunction,
                                strfunction=SCons.Tool.tex.TeXLaTeXStrFunction)
  
      env.AppendUnique(LATEXSUFFIXES=SCons.Tool.LaTeXSuffixes)
  
      from . import pdf
      pdf.generate(env)
  
      bld = env['BUILDERS']['PDF']
      bld.add_action('.tex', PDFTeXLaTeXAction)
      bld.add_emitter('.tex', SCons.Tool.tex.tex_pdf_emitter)
  
      # Add the epstopdf builder after the pdftex builder 
      # so pdftex is the default for no source suffix
      pdf.generate2(env)
  
      SCons.Tool.tex.generate_common(env)
docs: Add Builders and construction variables for pdftex to an Environment.