Revert "full Numpy"

This reverts commit 9322de7611f6e288db159a0be2ce110f8544ed97.
Revert "Initial position inside unity sphere"

This reverts commit 457adda9e53122918145117c92ccf47c6aa69bb1.
Revert "first step numpy - miss "next_step""

This reverts commit 252fd4836de327ef80d12429d2b997f460fa2551.