<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_adsorbate(self, molecule, ads_coord, repeat=None, reorient=True):
 """ Adds an adsorbate at a particular coordinate. Adsorbate represented by a Molecule object, and is positioned relative to the input adsorbate coordinate. Args: molecule (Molecule):
 molecule object representing the adsorbate ads_coord (array):
 coordinate of adsorbate position repeat (3-tuple or list):
 input for making a supercell of slab prior to placing the adsorbate reorient (bool):
 flag on whether to reorient the molecule to have its z-axis concurrent with miller index """

        if reorient:
            # Reorient the molecule along slab m_index
            sop = get_rot(self.slab)
            molecule.apply_operation(sop.inverse)
        struct = self.slab.copy()
        if repeat:
            struct.make_supercell(repeat)
        if 'surface_properties' in struct.site_properties.keys():
            molecule.add_site_property("surface_properties",
                                       ["adsorbate"] * molecule.num_sites)
        if 'selective_dynamics' in struct.site_properties.keys():
            molecule.add_site_property("selective_dynamics",
                                       [[True, True, True]] * molecule.num_sites)
        for site in molecule:
            struct.append(site.specie, ads_coord + site.coords, coords_are_cartesian=True,
                          properties=site.properties)
        return struct