TITLE SEWING MACHINE FOR DECORATIVE STITCHES RESEMBLING HAND SEWING, WITH FINISHED STITCHING IN VIEW DESCRIPTION FIELD OF APPLICATION This patent relates to the sewing machine sector. STATE OF THE ART Various mechanical, electric and electronic sewing machines are known. Sewing machines have a vertically-moving sewing needle situated above the flat bed, which sinks a short distance below said flat bed. Sewing machines are equipped with further mechanisms and/or lever assemblies for holding, hooking up and looping the thread carried by the sewing needle and/or a second thread coming from a bobbin housed underneath the flat bed. Some of said sewing machines (usually electric and electronic machines) also offer the opportunity to create decorative stitches or embroidery. Sewing machines are known that create decorative stitches resembling hand sewing, i.e. with the stitches in evidence. Said decorative stitches are formed mainly by a thread that is stitched through the fabric: on one side a sort of chain is created, while on the other side equally-spaced straight stitches are created that are aligned with one another. Modern sewing machines performing this type of stitch create the chain on the upper side of the fabric and the straight stitches on the underside of the fabric lying on the flat bed. The sewing machine can be adjusted to change the length of the straight stitches and their pitch, i.e. the distance between said straight stitches. Said decorative stitch is carried out with the fabric upside down, so that the straight stitches are ultimately visible on the outside of the finished garment. For some tailored garments, a double parallel row of decorative stitches as described above is required and it becomes necessary for the straight stitches in the two rows to lie exactly side by side with a uniform space between them. With modern machines, operators cannot control the precision of each row of stitches because the side of decorative stitching that will ultimately be in view is underneath during the stitching process. As a result, operators do not see this embroidery and cannot change the stitch position, length and pitch settings during the stitching process. To overcome all the above drawbacks, a new type of sewing machine has been designed and implemented, which is suited to obtain decorative stitches resembling hand sewing with the finished stitching in view. The object of the new sewing machine is to perform decorative stitching on the upper side of the fabric, which remains visible throughout the stitching process. Another object of the new sewing machine is to enable operators to see and control the stitching as it is being performed. A further object of the new sewing machine is to enable operators to timely adjust the stitch length and pitch settings as the stitching is being performed. These and other direct and complementary objects are achieved by the new sewing machine, which has the sewing needle, looping hook, thread take-up lever and needle bar situated underneath the flat bed. Above the flat bed, in line with the needle, are the crochet, the shuttle hook, the presser foot and the automatic fabric feed dog. DESCRIPTION OF AN EMBODIMENT The characteristics of the new sewing machine will be highlighted in greater detail in the following description with reference to the drawings, attached by way of a non-restrictive example. Figure 1 is a vertical cross section showing the flat bed (P), on which the fabric (T) to sew is placed. Underneath the flat bed (P), there is a shaft or needle bar (M) that moves vertically up and down, at the upper end of which the sewing needle (A) and the looping hook (U) are attached, so that the needle (A) is situated in a position lower than the hook (U). Both the needle (A) and the hook (U) on the needle bar (M) are driven by suitable electric, mechanical or pneumatic mechanisms, lever assemblies or actuators. Above the flat bed (P), there are the presser foot (S) and the automatic feed dog mechanism for the fabric (T). In particular, said presser foot (S) and automatic feed dog are arranged in such a way as to be in correspondence or aligned with the sewing needle (A) and hook (U). The needle (A) and hook (U) are moved vertically from underneath the flat bed (P) to above said flat bed (P), both perforating the fabric (T) as they do so. Once the row of stitches has been completed, the machine uses a thread trimmer with a mobile thread-guiding claw (O) - the front end (02) of which is shaped as shown in figure 2 - and a fixed blade (L). The thread-guiding claw (O) separates the two stretches of thread (F) lowered by the hook (U) and, on its return stroke, it exposes one of them so that it is cut by the fixed blade (L). The movement of the thread-guiding claw (O) is fine-adjusted so as to select only one of the two stretches of thread (F) lowered by the hook (U). Thus, with reference to the previous description and the enclosed drawings, the following claims are made.