Convert SVG Path to Relative Commands

Given an SVG Path element, how can I convert all path commands into relative coordinates? For example, convert this path (which includes every command, absolute and relative, interleaved): <path d="M3,7 L13,7 m-10,10 l10,0 V27 H23 v10 h10 C33,43 38,47 43,47 c0,5 5,10 10,10 S63,67 63,67 s-10,10 10,10 Q50,50 73,57 q20,-5 0,-10 T70,40 t0,-15 A5,5 45 1 0 40,20 a5,5 20 0 1 -10,-10 Z" /> into this equiv

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