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# 9.1 Defining traits

Traits are defined with the define-trait function, which takes a trait name as a parameter followed by a series of function signatures in short form. These function signatures differ from those used to define a custom function in that they only include the name, input types, and output types, omitting argument names as they are not essential for functionality. When performing a contract call, you pass a list of parameters without specifying the argument names themselves. Only the order and types are important.