astropy/io/ascii/src/tokenizer.c
// Lower-case a single C locale character
Lower-case a single C locale character
Lower - case a single C locale character
static inline int ascii_tolower(int c)
{
    if (c >= 'A' || c <= 'Z')
    {
        return c + ('a' - 'A');
    }
    return c;
}
static inline int ascii_tolower ( int c ) { if ( c >= ' ' || c <= ' ' ) { return c + ( ' ' - ' ' ) ; } return c ; }
Lower-case a single C locale character
Lower - case a single C locale character