def resource_headers(self, jobscript):
        """Given a :class:`~clusterjob.JobScript` instance, return a list of
        lines that encode the resource requirements, to be added at the top of
        the rendered job script
        """
        lines = []
        for (key, val) in jobscript.resources.items():
            if key in self.resource_replacements:
                slurm_key = self.resource_replacements[key]
                val = str(val).strip()
            else:
                slurm_key = key
            if not slurm_key.startswith('-'):
                if len(slurm_key) == 1:
                    slurm_key = '-%s' % slurm_key
                else:
                    slurm_key = '--%s' % slurm_key
            if val is None:
                continue
            if type(val) is bool:
                if val:
                    lines.append("%s %s" % (self.prefix, slurm_key))
            else:
                if slurm_key.startswith('--'):
                    lines.append('%s %s=%s'
                                  % (self.prefix, slurm_key, str(val)))
                else:
                    lines.append('%s %s %s'
                                 % (self.prefix, slurm_key, str(val)))
        return lines
Given a :class:`~clusterjob.JobScript` instance, return a list of
        lines that encode the resource requirements, to be added at the top of
        the rendered job script