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()