We discussed the existence of a radius of convergence for every power
series and how the series behaves inside and outside the circle of
convergence. We gave examples for convergence on the rim of the
circle. We noted that any Laurent expansion of a function defines two
convergent power series, for the positive and negative exponents, and
the coefficients of both are unique. A power series in (z-z_o) defines
a function S(z) inside the circle of convergence. We discussed
interchanging integration and summation when integrating g(z)S(z)
along a curve inside the circle of covergence, for any continuous
g(z), and interchanging differentiation and summation when
differentiating S.  We discussed multiplying and dividing power
series, and how to get the new coefficients in the results.

HW: we assigned sections 66,67