Fix Tracepoint example (#809)

diff --git a/examples/tracing/urandomread-explicit.py b/examples/tracing/urandomread-explicit.py
index e126192..17049c7 100755
--- a/examples/tracing/urandomread-explicit.py
+++ b/examples/tracing/urandomread-explicit.py
@@ -38,7 +38,7 @@
 
 # load BPF program
 b = BPF(text=bpf_text)
-b.attach_tracepoint("random:urandom_read", "printarg")
+b.attach_tracepoint(tp="random:urandom_read", fn_name="printarg")
 
 # header
 print("%-18s %-16s %-6s %s" % ("TIME(s)", "COMM", "PID", "GOTBITS"))