interface type is <code>nil</code>.
</p>

<pre class="ebnf">
InterfaceType  = "interface" "{" { InterfaceElem ";" } "}" .
InterfaceElem  = MethodElem | TypeElem .
MethodElem     = MethodName Signature .
MethodName     = identifier .
TypeElem       = TypeTerm { "|" TypeTerm } .
TypeTerm       = Type | UnderlyingType .
UnderlyingType = "~" Type .
</pre>

<p>

pkg reflect, method (Value) Len() int
pkg reflect, method (Value) MapIndex(Value) Value
pkg reflect, method (Value) MapKeys() []Value
pkg reflect, method (Value) Method(int) Value
pkg reflect, method (Value) MethodByName(string) Value
pkg reflect, method (Value) NumField() int
pkg reflect, method (Value) NumMethod() int
pkg reflect, method (Value) OverflowComplex(complex128) bool
pkg reflect, method (Value) OverflowFloat(float64) bool