nsec2gmt  (class=time #args=1,2) Formats integer nanoseconds since epoch as GMT timestamp. Leaves non-numbers as-is. With second integer argument n, includes n decimal places for the seconds part.
Examples:
nsec2gmt(1234567890000000000)    = "2009-02-13T23:31:30Z"
nsec2gmt(1234567890123456789)    = "2009-02-13T23:31:30Z"
nsec2gmt(1234567890123456789, 6) = "2009-02-13T23:31:30.123456Z"
nsec2gmtdate  (class=time #args=1) Formats integer nanoseconds since epoch as GMT timestamp with year-month-date. Leaves non-numbers as-is.
Example:
sec2gmtdate(1440768801700000000) = "2015-08-28".
sec2gmt  (class=time #args=1,2) Formats seconds since epoch as GMT timestamp. Leaves non-numbers as-is. With second integer argument n, includes n decimal places for the seconds part.
Examples:
sec2gmt(1234567890)           = "2009-02-13T23:31:30Z"
sec2gmt(1234567890.123456)    = "2009-02-13T23:31:30Z"
sec2gmt(1234567890.123456, 6) = "2009-02-13T23:31:30.123456Z"
sec2gmtdate  (class=time #args=1) Formats seconds since epoch (integer part) as GMT timestamp with year-month-date. Leaves non-numbers as-is.
Example:
sec2gmtdate(1440768801.7) = "2015-08-28".
