default boolean isEventThread() {
		return getThreadKey() == -1;
	}
Parse a step for the given thread key

<p>
The form of the spec must either be numeric, indicating some number of ticks, or
brace-enclosed Sleigh code, e.g., {@code "{r0=0x1234}"}. The latter allows patching machine
state during execution.

@param threadKey the thread to step, or -1 for the last thread or event thread
@param stepSpec the string specification
@param radix the radix
@return the parsed step
@throws IllegalArgumentException if the specification is of the wrong form
Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/time/schedule/Step.java