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fboundp  name ⇒  generalized-boolean
pronounced ,ef ’baund p\=e
name—a function name.
generalized-boolean—a generalized boolean.
Returns true if name is fbound; otherwise, returns false.
 (fboundp 'car) ⇒  true
 (fboundp 'nth-value) ⇒  false
 (fboundp 'with-open-file) ⇒  true
 (fboundp 'unwind-protect) ⇒  true
 (defun my-function (x) x) ⇒  MY-FUNCTION
 (fboundp 'my-function) ⇒  true
 (let ((saved-definition (symbol-function 'my-function)))
   (unwind-protect (progn (fmakunbound 'my-function)
                          (fboundp 'my-function))
     (setf (symbol-function 'my-function) saved-definition)))
⇒  false
 (fboundp 'my-function) ⇒  true
 (defmacro my-macro (x) `',x) ⇒  MY-MACRO
 (fboundp 'my-macro) ⇒  true
 (fmakunbound 'my-function) ⇒  MY-FUNCTION
 (fboundp 'my-function) ⇒  false
 (flet ((my-function (x) x))
   (fboundp 'my-function)) ⇒  false
Should signal an error of type type-error if name is not a function name.
symbol-function , fmakunbound , fdefinition
It is permissible to call symbol-function on any symbol that is fbound.
fboundp is sometimes used to “guard” an access to the function cell, as in:
(if (fboundp x) (symbol-function x))
Defining a setf expander F does not cause the setf function (setf F) to become defined.