Array ( [per_page] => 15 [page] => 1 [extras] => original_format,url_sq, url_t, url_s, url_q, url_m, url_n, url_z, url_c, url_l, url_o,o_dims )string(6) "square"
Thumb_size options only square,thumbnail,small,medium,medium_640,large,original
see function buildPhotoURL()