FprintStack prints the stack trace returned by runtime.Stack to the writer.

FuncName is similar to runtime.Caller, but instead to return program counter or function name with full path, funcName returns just function name, separated filename, and line number.

PrintStack prints to standard error the stack trace returned by runtime.Stack by starting from stackLevel.

PrintStackForTest prints to io.Writer the stack trace returned by runtime.Stack and processed to proper format to be shown in test output by starting from stackLevel.

PackageRegexp is regexp search that help us find those lines that includes function calls in our package and its sub packages.

StackInfo has two parts.