  The main result of the paper is a formula for the fundamental group of the
coarse moduli space of a topological stack. As an application, we find simple
general formulas for the fundamental group of the coarse quotient of a group
action on a topological space in terms of the fixed point data. The formulas
seem, surprisingly, to be new. In particular, we recover, and vastly
generalize, results of Armstrong, Bass, Higgins, Rhodes.
