In preparation for careful definitions for limits of function we
defined: accumulation point, set complement, open set, connected set,
boundary point of a set, a domain, and a region. We defined what it
means for a function to have a limit at a point z. We sketched proofs
about limits of sums, products, quotients and composition of
functions. We proved f(z)=|z| is continuous at all z.

HW: none assigned