Assign to v the value stored in the map m for the key k.Explain what happens if there is no entry for k in m.
v := m[k]
v, ok := m[k]
v = m.get(k);
local v=m[k]
$v = $m{$k};
$v = $m{$k} // 'foobar';
v = m[k]
v = m.get(k, "default value")
v = m.get(k)
No security, no password. Other people might choose the same nickname.