Return true if the object is a frame object.
Frame objects provide these attributes:
f_back next outer frame object (this frame's caller)
f_builtins built-in namespace seen by this frame
f_code code object being executed in this frame
f_globals global namespace seen by this frame
f_lasti index of last attempted instruction in bytecode
f_lineno current line number in Python source code
f_locals local namespace seen by this frame
f_trace tracing function for this frame, or None
f_trace_lines is a tracing event triggered for each source line?
f_trace_opcodes are per-opcode events being requested?
clear() used to clear all references to local variables