This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.

MemberQ

 MemberQ[list, form]returns True if an element of list matches form, and False otherwise. MemberQ[list, form, levelspec]tests all parts of list specified by levelspec.
• form can be a pattern.
• The first argument of MemberQ can have any head, not necessarily List.
• MemberQ[list, form] immediately tests whether any expression in list matches form; Element[x, dom] asserts that x is an element of the symbolic domain dom.
• MemberQ uses standard level specifications:
 n levels 1 through n Infinity levels 1 through Infinity {n} level n only {n1,n2} levels n1 through n2
• The default value for levelspec in MemberQ is {1}.
• A positive level n consists of all parts of expr specified by n indices.
• A negative level -n consists of all parts of expr with depth n.
• Level -1 consists of numbers, symbols and other objects that do not have subparts.
• Level 0 corresponds to the whole expression.
• With the option setting , MemberQ looks at heads of expressions, and their parts.
Test whether 2 is a member of a list:
 Out[1]=
 Scope   (2)
 Applications   (1)
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