remove demos and add examples

Signed-off-by: varun-r-mallya <varunrmallya@gmail.com>

examples/pybpf3.py

@@ -0,0 +1,49 @@
+from pythonbpf import *
+from pylibbpf import *
+import sys
+from ctypes import c_void_p, c_int64, c_uint64
+
+@bpf
+@map
+def last() -> HashMap:
+    return HashMap(key=c_uint64, value=c_uint64, max_entries=3)
+
+@bpf
+@section("tracepoint/syscalls/sys_enter_clone")
+def do_trace(ctx: c_void_p) -> c_int64:
+    key = 0
+    tsp = last().lookup(key)
+    if tsp:
+        kt = ktime()
+        delta = (kt - tsp)
+        if delta < 1000000000:
+            time_ms = (delta // 1000000)
+            print(f"Clone syscall entered within last second, last {time_ms} ms ago")
+        last().delete(key)
+    else:
+        kt = ktime()
+        last().update(key, kt)
+    return c_int64(0)
+
+@bpf
+@bpfglobal
+def LICENSE() -> str:
+    return "GPL"
+
+b = BPF()
+# autoattaches tracepoints
+b.load_and_attach()
+
+def main():
+    try:
+        with open("/sys/kernel/debug/tracing/trace_pipe", "r") as f:
+            for line in f:
+                sys.stdout.write(line)
+                sys.stdout.flush()
+    except KeyboardInterrupt:
+        pass
+    except PermissionError:
+        sys.stderr.write("Need root privileges to read trace_pipe\n")
+
+if __name__ == "__main__":
+    main()