Solution (source code)

= Solution

A sequence converges to $x\in X$ when
$$
\boxed{\forall\varepsilon>0\;\exists N\;\forall n\geq N:\ d(x_n,x)<\varepsilon}.
$$
The phrase <convergent sequence> requires the limit to belong to the stated <metric space>; convergence in a larger ambient space alone does not suffice.