def append(self, species, coords, coords_are_cartesian=False,
               validate_proximity=False, properties=None):
        """
        Append a site to the structure.

        Args:
            species: Species of inserted site
            coords (3x1 array): Coordinates of inserted site
            coords_are_cartesian (bool): Whether coordinates are cartesian.
                Defaults to False.
            validate_proximity (bool): Whether to check if inserted site is
                too close to an existing site. Defaults to False.
            properties (dict): Properties of the site.

        Returns:
            New structure with inserted site.
        """
        return self.insert(len(self), species, coords,
                           coords_are_cartesian=coords_are_cartesian,
                           validate_proximity=validate_proximity,
                           properties=properties)
Append a site to the structure.

        Args:
            species: Species of inserted site
            coords (3x1 array): Coordinates of inserted site
            coords_are_cartesian (bool): Whether coordinates are cartesian.
                Defaults to False.
            validate_proximity (bool): Whether to check if inserted site is
                too close to an existing site. Defaults to False.
            properties (dict): Properties of the site.

        Returns:
            New structure with inserted site.