How to use the pyuvdata._miriad.hdaccess function in pyuvdata

rv.append(c)
                offset += o

            if itype == "a":
                rv = "".join(rv)
        else:
            t, offset = _miriad.hread_init(h)
            assert t == "b"

            for t in itype:
                v, o = _miriad.hread(h, offset, t)
                rv.append(v)
                offset += o

        _miriad.hdaccess(h)

        if len(rv) == 1:
            return rv[0]
        elif type(rv) == str:
            return rv
        else:
            return np.array(rv)

def _wrhd_special(self, name, val):
        """Provide write access to special header items of type '?' to _wrhd."""
        if name == "freqs":
            h = self.haccess(name, "write")
            _miriad.hwrite(h, 0, val[0], "i")
            offset = 8

            for i, v in enumerate(val[1:]):
                if i % 3 == 0:
                    _miriad.hwrite(h, offset, v, "i")
                else:
                    _miriad.hwrite(h, offset, v, "d")
                offset += 8

            _miriad.hdaccess(h)
        else:
            raise ValueError("Unknown special header: " + name)

try:
                    c, o = _miriad.hread(h, offset, "i")
                    rv.append(c)
                    offset += 8

                    c, o = _miriad.hread(h, offset, "d")
                    rv.append(c)
                    offset += 8

                    c, o = _miriad.hread(h, offset, "d")
                    rv.append(c)
                    offset += 8
                except IOError:
                    break

            _miriad.hdaccess(h)
            return rv
        else:
            raise ValueError("Unknown special header: " + name)

def items(self):
        """
        Get the list of available header items.

        Returns
        -------
        list of str
            list of available header items
        """
        items = []

        for i in itemtable:
            try:
                _miriad.hdaccess(self.haccess(i, "read"))
                items.append(i)
            except IOError:
                pass
        return items