OBJECT is either a string or a buffer. Optional arguments START and
END are character positions specifying which portion of OBJECT for
computing the hash. If BINARY is non-nil, return a 40-byte unibyte
-string; otherwise returna 40-character string.
+string; otherwise return a 40-character string.
Note that SHA-1 is not collision resistant and should not be used
for anything security-related. See `secure-hash' for