code: def _sphinx_build(self, kind):
          
          if kind not in ('html', 'latex'):
              raise ValueError('kind must be html or latex, '
                               'not {}'.format(kind))
  
          cmd = ['sphinx-build', '-b', kind]
          if self.num_jobs:
              cmd += ['-j', str(self.num_jobs)]
          if self.warnings_are_errors:
              cmd += ['-W', '--keep-going']
          if self.verbosity:
              cmd.append('-{}'.format('v' * self.verbosity))
          cmd += ['-d', os.path.join(BUILD_PATH, 'doctrees'),
                  SOURCE_PATH, os.path.join(BUILD_PATH, kind)]
          return subprocess.call(cmd)
docs: Call sphinx to build documentation.
  
          Attribute `num_jobs` from the class is used.
  
          Parameters
          ----------
          kind : {'html', 'latex'}
  
          Examples
          --------
          >>> DocBuilder(num_jobs=4)._sphinx_build('html')