  We use an example to provide evidence for the statement: the
Vassiliev-Kontsevich invariants $k_n$ of a knot (or braid) $k$ can be redefined
so that $k = \sum_0^\infty k_n$. This constructs a knot from its
Vassiliev-Kontsevich invariants, like a power series expansion. The example is
pure braids on two strands $P_2\cong \mathbb{Z}$, which leads to solving
$e^\tau=q$ for $\tau$ a Laurent series in $q$. We set $\tau = \sum_1^\infty
(-1)^{n+1} (q^n - q^{-n})/n$ and use Parseval's theorem for Fourier series to
prove $e^\tau=q$. Finally we describe some problems, particularly a Plancherel
theorem for braid groups, whose solution would take us towards a proof of
$k=\sum_0^\infty k_n$.
