Blend

I'm new to grasshopper - so am hoping there's a really simple answer to this that I just can't work out.

I want to replicate rhino's 'blend'.  I've looked at bezier span, curve and biarc - but they don't give the same curvature as just 'blend' in rhino.  I want to draw a curve from the end of one line to the end of another - not a mean curve between them.

thanks in advance