code: def local_path_export(at_start=True, env_cmd=None):
      
      paths = [get_bcbio_bin()]
      if env_cmd:
          env_path = os.path.dirname(get_program_python(env_cmd))
          if env_path not in paths:
              paths.insert(0, env_path)
      if at_start:
          return "export PATH=%s:\"$PATH\" && " % (":".join(paths))
      else:
          return "export PATH=\"$PATH\":%s && " % (":".join(paths))
docs: Retrieve paths to local install, also including environment paths if env_cmd included.